diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index f2d7cea86ffe..191c329e482a 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -38,10 +38,7 @@ static bool cgroup_no_v1_named; */ static struct workqueue_struct *cgroup_pidlist_destroy_wq; -/* - * Protects cgroup_subsys->release_agent_path. Modifying it also requires - * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. - */ +/* protects cgroup_subsys->release_agent_path */ static DEFINE_SPINLOCK(release_agent_path_lock); bool cgroup1_ssid_disabled(int ssid) @@ -775,22 +772,29 @@ void cgroup1_release_agent(struct work_struct *work) { struct cgroup *cgrp = container_of(work, struct cgroup, release_agent_work); - char *pathbuf = NULL, *agentbuf = NULL; + char *pathbuf, *agentbuf; char *argv[3], *envp[3]; int ret; - mutex_lock(&cgroup_mutex); + /* snoop agent path and exit early if empty */ + if (!cgrp->root->release_agent_path[0]) + return; + /* prepare argument buffers */ pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); - agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); - if (!pathbuf || !agentbuf || !strlen(agentbuf)) - goto out; + agentbuf = kmalloc(PATH_MAX, GFP_KERNEL); + if (!pathbuf || !agentbuf) + goto out_free; - spin_lock_irq(&css_set_lock); - ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns); - spin_unlock_irq(&css_set_lock); + spin_lock(&release_agent_path_lock); + strlcpy(agentbuf, cgrp->root->release_agent_path, PATH_MAX); + spin_unlock(&release_agent_path_lock); + if (!agentbuf[0]) + goto out_free; + + ret = cgroup_path_ns(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns); if (ret < 0 || ret >= PATH_MAX) - goto out; + goto out_free; argv[0] = agentbuf; argv[1] = pathbuf; @@ -801,11 +805,7 @@ void cgroup1_release_agent(struct work_struct *work) envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; envp[2] = NULL; - mutex_unlock(&cgroup_mutex); call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); - goto out_free; -out: - mutex_unlock(&cgroup_mutex); out_free: kfree(agentbuf); kfree(pathbuf);